The invention described and claimed herein is related generally to vibrating conveyors, and more specifically to vibrating conveyors which seek to minimize vibrational movement of the material-conveying member in a plane which is substantially normal to the path of conveyance.
For many years vibratory conveyors of various constructions have been used in manufacturing processes for particle displacement along a given path of conveyance. A typical conventional conveyor generally employs a material-conveying member which is vibrated at an angle relative to the path of conveyance, thereby introducing both horizontal and vertical vibrational components to the material-conveying member. Such horizontal and vertical vibrational forces effectively cause the material being conveyed to bounce along the path of conveyance from one end of the conveyor to the other.
It has long since been well recognized that vibrational forces generated normal to the path of conveyance (generally vertical components) are undesirable for a number of reasons. One such reason is that the bouncing nature of such conveyors makes it difficult for workers to handle the material which is being conveyed along the path of conveyance. Also, such normal components of force tend to damage delicate materials being conveyed, and cause a substantial amount of dust and other particles to become airborne, thereby creating an undesirable environment which the worker must endure.
In addition to the above disadvantages, conveyors of the conventional type which have significant vertical components of force normal to the path of conveyance can cause substantial damage to their supporting structures through repeated transmission of such vibrational forces thereto. With such conveyors typically reciprocating at well over 200 cycles per minute, the transmission of such vibrational forces to the supporting structure of the conveyor transmits vibrations of the structural support members, causing deterioration and possible failure of the joints therebetween. Moreover, the repeated impacts of the bouncing material within the material-conveying member causes substantial noise which contributes to the undesirable environment created by such conveyors. For a typical conveyor pan weighing 500 pounds and vibrating at 400 cycles per minute, a seemingly minor vertical vibrational displacement of 0.004 inches translates into approximately nine (9) pounds of cyclical vertical force being transmitted to the supporting structure. Such repeated vibratory forces may eventually cause substantial stresses and damage to the supporting structure.
Attempts have been made in the past to eliminate the numerous problems associated with such conventional conveyors by minimizing those components of vibratory force which are normal to the path of conveyance. For instance, one commercial device known as the SLIPSTICK conveyor, manufactured by Triple/S Dynamic's, Inc., utilizes symmetrically balanced rotating eccentric weights and a gear coupled drive mechanism to provide a horizontal differential drive motion which is substantially, if not completely, devoid of vertical vibrational components. Such horizontal differential motion is characterized by a slow-advance, quick return action which effectively glides the product down the material-conveying member without substantial vertical vibration.
Another known commercial device which employs a highly similar vibrational drive system is disclosed in U.S. Pat. No. 5,131,525, issued to Musschott on Jun. 21, 1992. Again, the drive system utilizes symmetrically balanced rotating eccentric weights to cause a horizontal differential motion which is substantially devoid of vertical vibrational components. The apparatus in the above patent, however, allows for variance of the position of the vibration generating means along the length of the material-conveying member so as to reduce horizontal vibratory forces which may occur in the material-conveying member.
Although the above known commercial devices have been somewhat effective in minimizing the generally vertical vibrational forces normal to the path of conveyance, such devices are deficient in that they ignore the effects of a very important source of such normal vibratory forces--the relative motion of the material-conveying member itself. If the material-conveying member is supported in such a manner that it is forced to oscillate through a pendular or arcuate motion, there will be a necessary and significant component of vibration normal to the path of conveyance, regardless of the direction of the vibratory force which is transmitted thereto. As stated previously, small vertical deflections can generate undesirable vertical forces.
As is the case in each of the above-described commercial devices, the material-conveying member is supported or suspended from its supporting surface by a pendulum-type supporting device which necessarily introduces a substantial vibrational force which is normal to the path of conveyance. Although the total stroke distance through which a typical conveyor operates is relatively short, as shown herein, the large mass of such conveyors, and the high speed at which they operate, makes the relative motion of the material-conveying member a significant factor which must be considered in attempting to eliminate undesirable vibrational forces which are normal to the path of conveyance.
As used herein and throughout the appended claims, the terms "pendulum" or "pendular," when used in reference to a conveyor supporting device, and the relative motion caused thereby in the material-conveying member of such a conveyor, means those supporting devices which utilize pendulum arms or leaf springs to support the material-conveying member, and the relative motion in which a material-conveying member is caused to move as a result of such pendulum arms or leaf springs.
Industries requiring conveyance of delicate materials have long since sought a solution to the above-mentioned problems which are incident to the use of conventional conveyors. A continuing search for quality and efficiency in producing competitive products throughout every industry has caused such industries to seek conveyors having improved conveyance characteristics. Through the use of our unique conveyor support mechanism described hereinbelow, we are now able to significantly reduce to negligible levels any vibrational components of force generally normal to the path of conveyance which are generated through the relative motion of the material-conveying member itself.